The invention relates to a hearing aid device to be worn in the ear comprising a housing consisting of two shells of which the first has the outer contours of an individually fitted ear adapter and the second, whose floor is penetrated by access openings and adjustment elements of the operating elements of the hearing aid structure, is attached to the open side of the first shell for closing it.
Given in-ear hearing aids of the "custom-made version", i.e., such as have an at least largely prefabricated device which is inserted into a fitted ear adapter, it has proven expedient to design the prefabricated part of the device as an assembly unit so as to be easily interchangeable. To that end, the actual installation space should be situated in the cavity of a fitted ear adapter which is covered with a closing plate that exhibits an opening in its center into which an assembly unit is inserted which carries the operating elements (volume control, matching regulator, switch, microphone, battery compartment). Since, however, the assembly unit to be employed must be a matter of an element suitable for all dimensions occurring in the care of hearing-impaired persons, a lateral edge always remains in the cover plate upon insertion, said lateral edge being perceptible on the finished device. However, an inconspicuous structure is preferred for a hearing aid; i.e., for cosmetic reasons, the assembly unit should not be visible on the device. Moreover, given small dimensions of the ear, only a narrow ring of the cover plate remains, its stability being only slight for the support of the assembly unit.